The present invention relates to means for securing a saw blade to an arbor shaft, and more particularly provides means for securing the blade to the shaft and facilitating the removal of the saw blade from the arbor shaft.
In prior art arrangements, a saw blade is carried by an arbor shaft including an arbor backing plate where one side of the saw blade abuts the arbor plate and an arbor nut is threaded onto the arbor shaft to secure the saw blade by pressing against an opposite side of the saw blade to urge the saw blade against the arbor plate.
In prior art arrangements, removal of the arbor nut is difficult inasmuch as when a wrench is placed on the arbor nut and rotated, the arbor shaft and the saw blade are likewise rotated.
Various means have been utilized for securing the saw blade to permit independant rotation to the arbor nut on the arbor shaft to loosen the arbor nut so the saw blade can be removed. In one instance where the saw blade is carried on a table saw having a table through which the blade extends a block placed on the table to engage the saw teeth to prevent rotation of the saw blade and permit independant rotation of the arbor nut. Such an arrangement is, at best, awkward and dangerous and in some instances where a fine tooth saw blade is utilized it is difficult to securely engage the particular saw tooth so slippage occurs with the liklihood of damage to the person attempting to remove the saw blade.
In other instances a lock has been provided as part of the saw assembly to lock the arbor shaft or the blade when the blade is to be changed but such arrangements are expensive, and generally must be incorporated in the saw assembly upon manufacture.
No prior art arrangement permitting removal of the blade without locking the shaft is known.
The known art includes U.S. Pat. No. 3,705,611--Sakamoto which teaches an arrangement for including parallel spaced circular saw blades where retainer means are provided for the saw blade during changing but does not include any means to facilitate independant rotation of the arbor nut upon the arbor shaft.
The prior further includes U.S. Pat. No. 3,266,535--Brodie, which teaches an adjustable coupling between a blade and the driven spindle of a portable power saw for release of a blade whenever the blade encounters resistance to rotation. The Brodie reference, like the Sakamoto reference, and the prior art does not teach means for release of the arbor nut from the arbor shaft without locking the blade or arbor shaft.